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Theorem cnconst 23208
Description: A constant function is continuous. (Contributed by FL, 15-Jan-2007.) (Proof shortened by Mario Carneiro, 19-Mar-2015.)
Assertion
Ref Expression
cnconst (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ (𝐡 ∈ π‘Œ ∧ 𝐹:π‘‹βŸΆ{𝐡})) β†’ 𝐹 ∈ (𝐽 Cn 𝐾))

Proof of Theorem cnconst
StepHypRef Expression
1 fconst2g 7221 . . . 4 (𝐡 ∈ π‘Œ β†’ (𝐹:π‘‹βŸΆ{𝐡} ↔ 𝐹 = (𝑋 Γ— {𝐡})))
21adantl 480 . . 3 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹:π‘‹βŸΆ{𝐡} ↔ 𝐹 = (𝑋 Γ— {𝐡})))
3 cnconst2 23207 . . . . 5 ((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ) ∧ 𝐡 ∈ π‘Œ) β†’ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾))
433expa 1115 . . . 4 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾))
5 eleq1 2817 . . . 4 (𝐹 = (𝑋 Γ— {𝐡}) β†’ (𝐹 ∈ (𝐽 Cn 𝐾) ↔ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾)))
64, 5syl5ibrcom 246 . . 3 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹 = (𝑋 Γ— {𝐡}) β†’ 𝐹 ∈ (𝐽 Cn 𝐾)))
72, 6sylbid 239 . 2 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹:π‘‹βŸΆ{𝐡} β†’ 𝐹 ∈ (𝐽 Cn 𝐾)))
87impr 453 1 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ (𝐡 ∈ π‘Œ ∧ 𝐹:π‘‹βŸΆ{𝐡})) β†’ 𝐹 ∈ (𝐽 Cn 𝐾))
Colors of variables: wff setvar class
Syntax hints:   β†’ wi 4   ↔ wb 205   ∧ wa 394   = wceq 1533   ∈ wcel 2098  {csn 4632   Γ— cxp 5680  βŸΆwf 6549  β€˜cfv 6553  (class class class)co 7426  TopOnctopon 22832   Cn ccn 23148
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-10 2129  ax-11 2146  ax-12 2166  ax-ext 2699  ax-sep 5303  ax-nul 5310  ax-pow 5369  ax-pr 5433  ax-un 7746
This theorem depends on definitions:  df-bi 206  df-an 395  df-or 846  df-3an 1086  df-tru 1536  df-fal 1546  df-ex 1774  df-nf 1778  df-sb 2060  df-mo 2529  df-eu 2558  df-clab 2706  df-cleq 2720  df-clel 2806  df-nfc 2881  df-ne 2938  df-ral 3059  df-rex 3068  df-rab 3431  df-v 3475  df-sbc 3779  df-csb 3895  df-dif 3952  df-un 3954  df-in 3956  df-ss 3966  df-nul 4327  df-if 4533  df-pw 4608  df-sn 4633  df-pr 4635  df-op 4639  df-uni 4913  df-iun 5002  df-br 5153  df-opab 5215  df-mpt 5236  df-id 5580  df-xp 5688  df-rel 5689  df-cnv 5690  df-co 5691  df-dm 5692  df-rn 5693  df-res 5694  df-ima 5695  df-iota 6505  df-fun 6555  df-fn 6556  df-f 6557  df-fv 6561  df-ov 7429  df-oprab 7430  df-mpo 7431  df-1st 7999  df-2nd 8000  df-map 8853  df-topgen 17432  df-top 22816  df-topon 22833  df-cn 23151  df-cnp 23152
This theorem is referenced by:  xrge0mulc1cn  33575  cxpcncf2  45316
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